September 11, 2006, marks the closing date for comments in the Federal Aviation Administration’s proposed rule entitled “Safe, Efficient Use and Preservation of the Navigable Airspace.” This proposed rule, if approved, would cost businesses and consumers billions of dollars for little benefit. It should be stopped now.

Many of us know little more about the FAA other than the announcements on planes that FAA regulations require us to turn off cell phones and other electronic devices. For decades, the FAA has reasonably regulated towers that may pose a physical hazard for aircraft, particularly in takeoff and landing approaches to airports. In its new proceeding, the FAA seeks to regulate not merely physical structures but spectrum usage, even in bands remote from those used by the aviation industry.

The Federal Communications Commission already regulates spectrum for non-governmental uses and the National Telecommunications and Information Administration regulates governmental uses. Now the FAA wants prior notification of every adjustment to transmission noise on towers in a wide swath of spectrum primarily used by the broadcast, wireless, and satellite industries — much, if not most, of the commercial industry. This is far more burdensome than currently required by the FCC.

Exactly how much of a burden would be these new FAA rules? The FAA estimates that fewer than 27,000 entities would be affected, each of which would “on occasion” file changes as necessary. The FAA assumes that the cost of filing would range between $10 for an individual and $445 for a consulting firm. The FAA measures the total administrative cost of filing to the private sector at $13.7 million over 10 years, or $1.37 million annually. The agency assumes that its own costs will be $19.9 million, greater than that of the private sector.

Comments thus far in the proceeding have focused on these administrative costs. The FCC observes that, rather than just 27,000 entities filing on occasion, the FAA should expect many more than 1 million filings annually given the breadth of the filing requirement. Private companies and trade associations note that the cost of underlying engineering studies required for many filings will well exceed $1,000 even before accounting for the administrative filing costs. These comments indicate that the annual administrative cost of filing under new FAA rules could exceed $1 billion, rather than the $1.37 million the FAA estimates.

Even if the FAA proceeding were merely a harmless paper shuffle, the costs are quite staggering. But the administrative costs of filing pale in comparison to the regulatory uncertainty that spectrum licensees face when they file with the FAA. Surely, the purpose of filing with the FAA is not merely to collect useless records but to give the FAA the opportunity to have public comment and review of every alteration in spectrum usage.

Layers of FAA review presage months of delay and the unpredictable possibility of denial. The cost of filing will be large; the cost of promoting and defending every filing larger still; and the cost of preparing for an uncertain outcome incalculable. Thus far, comments in this proceeding have been too polite, and perhaps too wary, to tell the FAA this obvious circumstance.

In contrast to the large and staggering costs of the proposed rule, the FAA finds only two “qualitative” benefits. These are to “enhance the safety of air navigation aids” and to “protect the flying public from signal interference.” The FAA documents are surprisingly devoid of specific examples of shortfalls in the safety of navigation aids or a flying public unprotected from signal interference tied to the spectrum bands to be regulated.

The FAA has estimated the costs and benefits of the proposed rule. But many other relevant costs and benefits have not been adequately considered.

Everyone is in favor of air traffic safety; even one mishap is one too many. But this proposed rule is not based on remedying a documented problem but resolving a theoretical and undocumented harm. Moreover, excessive spectrum interference is already unlawful under federal rules and is regulated by other agencies. The direct cost of the new FAA proposed rule is not a few million dollars but a few billion. But the greatest cost may well be the loss of the legitimacy and predictability of the regulatory process.

A former FCC commissioner, Mr. Furchtgott-Roth is president of Furchtgott-Roth Economic Enterprises. He can be reached at hfr@furchtgott-roth.com.